考虑能耗优化的双足步行机器人柔性关节研究

Compliant joint for biped robot considering energy consumption optimization

为了优化双足步行机器人行走过程中的能量消耗,建立机器人的柔性踝关节和柔性膝关节,分析在机器人单腿支撑阶段,矢状面运动中柔性关节的刚度对关节电机输出转矩和能量消耗的影响。首先,建立双足步行机器人的5连杆模型,分别在该模型的踝关节和膝关节对柔性进行改进;其次,采用基于零力矩点(zero moment point,ZMP)稳定判据的步态规划方法,通过给定ZMP轨迹获取机器人质心轨迹,插值得到机器人在刚性路面的离线步态;最后,基于改进的柔性关节5连杆步行机器人模型,分别采用拉格朗日方程解析法和虚拟样机动力学仿真法,分析柔性踝关节和膝关节的刚度对关节电机输出转矩和能量消耗的影响。研究结果表明:适当选择柔性关节的刚度可以有效地减小关节电机的输出转矩和能量消耗;柔性踝关节和膝关节分别存在1个最佳刚度,在此刚度下关节电机的能量消耗可以降到最小,与解析法中刚性关节相比分别减小89.87%和90.11%,与动力学仿真中刚性关节相比分别减小88.66%和81.23%。

In order to optimize the energy consumption of biped robot while walking, the compliant joint for biped walking robots was proposed to investigate the influence of ankle joint and knee joint stiffness on motor torque and energy consumption of the sagittal plane motion during the single support phase. Firstly, an improved model of the five-link biped robot was established, which is the theoretical foundation of the compliant joint. Then, with gait planning based on natural zero moment point （ZMP） trajectory, the robot＇s center of mass （COM） rack was obtained by setting ZMP trajectory, and the gait on a rigid path was acquired by interpolation. Finally, both the Lagrange equations analytic method and dynamic simulations were performed to analyze the influences of compliant joint stiffness on motor torque and energy consumption based on the improved model of the five-link biped robot. The results show that the compliant joint can reduce the joint motor torque and energy consumption effectively. There is an optimal stiffness of the compliant ankle joint and knee joint respectively, which can minimize the motor energy consumption with a reduction of 89.87% and 90.11% in analytic method, as well as 88.66% and 81.23% in dynamic simulations.